JPS598291B2 - Production method of heat-resistant poly(2,6-dimethylparaphenylene ether) - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a process for producing heat-resistant poly(2,6-dimethylparaphenylene ether).

Although poly(2,6-dimethyl paraphenylene ether) is a thermoplastic resin with excellent heat resistance, this resin has a drawback in its resistance to oxidative deterioration during heating. Conventionally, it has been thought that the cause of this is the presence of an OH group in the terminal group of poly(2,6-dimethylparaphenylated scuteyl), and therefore, this terminal group is esterified, methyl etherified, -Various stabilization methods such as cyanovinyl etherification have been proposed. However, in all of these methods, a stabilizer is not added at the same time during the polymerization reaction of 2,6-dimethylphenol, and once the poly(2,6-dimethylphenol is
After the previously used polymerization catalyst was separated and removed from this polymer, a stabilizer was added and the reaction was carried out.

Therefore, a stabilization reaction was required separately from the polymerization of 2,6-dimethylphenol, and the operation was complicated. The present inventors have developed a method for producing poly(2,6-dimethyl paraphenylene ether) with excellent heat resistance through simple operations by polymerizing 2,6-dimethylphenol in the coexistence of a polymerization catalyst and a stabilizer. As a result of intensive studies, we have arrived at the present invention.

That is, in the present invention, in the presence of a copper-amine catalyst, 2.
When polymerizing 6-dimethylphenol using oxygen-containing gas, 0.0
Heat-resistant poly(2,6-
The present invention relates to a method for producing dimethyl paraphenylene ether). The 2,6-diphenylphenol used in the method of the present invention binds to the terminal 0H group of poly(2,6-dimethylparaphenylene ether), which is a polymer of 2,6-dimethylphenol, and stabilizes it. This is thought to improve heat resistance. The appropriate amount of 2,6-diphenylphenol added is 0.05 to 10 wt% based on 2,6-dimethylphenol.

If the amount added is less than this, the heat resistance effect of the polymer will not be exhibited, and if the amount added is more than this, the polymer yield will decrease, which is not preferable. The timing of adding 2,6-diphenylphenol may be at the time of starting the polymerization of 2,6-dimethylphenol using oxygen in the presence of a copper-amine catalyst, or during the polymerization, or once it has been polymerized. In that case, without separating or removing the polymerization catalyst,
Further, when separated and removed, it is necessary to add a new polymerization catalyst.

The polymerization catalyst is a conventionally known copper-amine catalyst used in the polymerization of di-substituted phenols, such as copper bromide-pyridine, copper bromide-N,N,N',N'-tetramethyl-1,
3-butanediamine and the like are used.

Further, as the solvent, an organic compound inert to the oxidative polymerization reaction, such as benzene, chlorobenzene, dichlorobenzene, or nitrobenzene, is used.

The reaction temperature is 20 to 50°C, which is the polymerization temperature of 2,6-dimethylphenol, and particularly preferably around 30°C. Below this temperature, the polymerization reaction rate decreases,
Moreover, at temperatures above this temperature, the proportion of side reaction products such as diphenoquinone produced increases, making it impossible to obtain a high molecular weight polymer. Further, as the oxygen-containing gas, pure oxygen, air, a mixed gas of oxygen diluted with an inert gas, etc. are used.

As detailed above, by carrying out the method of the present invention, 2,6-dimethylphenol can be polymerized to produce poly(2,6-dimethylparaphenylene ether) with excellent heat resistance in high yield. It can be manufactured in

Next, the method of the present invention will be specifically explained using Examples. In the examples, the heat resistance of the polymers was compared by measuring the weight loss start temperature in air for purified polymers using a differential calorimeter 8085 (manufactured by Rigaku Denki). Examples 1 to 5 , Reference Examples 1 to 3 and Comparative Example 1
After purging a cylindrical separable flask with an internal volume of 200 m1 equipped with a stirrer, a gas inlet/outlet, a thermocouple, and a raw material dropping load with nitrogen, 156 m1 of benzene, 0.299 g of cuprous bromide and 3.219 g of pyridine were added as a catalyst. te30
Heated and maintained at ℃, oxygen 300ml 1/7! ! While stirring at 500 rpm, a raw material solution prepared by dissolving 20 ml of 26-dimethylphenol and a small amount of 2,6-diphenylphenol in 30 ml of benzene was added dropwise to 18-ml to carry out polymerization.

After 6 hours of reaction, the polymerization mixture was poured into a 0.5% aqueous hydrochloric acid solution and methanol, followed by reprecipitation, washing with methanol, and drying to obtain a crude polymer of poly(2,6-dimethylparaphenylene ether).

Next, this crude polymer was dissolved in benzene again, and the clear solution, which was naturally filtered through Fuchigami paper, was poured into methanol and reprecipitated.
A purified polymer was obtained by drying. Comparative Example 1 was carried out in the same manner as in the above Example, except that only 2,6-dimethylphenol dissolved in benzene was used as the raw material solution. Table 1 shows the polymer yield and weight loss start temperature at that time. Examples 6 to 10 Additive-free poly(2,6-dimethylparaphenol) was prepared in the same manner as in Examples 1 to 5 above, except that only 2,6-dimethylphenol dissolved in benzene was used as the raw material solution. Nylene ether) was obtained, and without removing the catalyst, a small amount of 2,6-diphenylphenol was added and the reaction was further carried out for a predetermined period of time while introducing oxygen.

Table 2 shows the weight loss start temperature at that time. Comparative example
2-5 The same procedure as in Example 8 was carried out except that the phenols listed in Table 3 were added instead of 2,6-diphenylphenol.

The polymer yield and weight loss start temperature at that time were
Shown in the table. * Added phenol 1 wt % (based on dimethylphenol), reaction time after addition of phenol * 2 hr In Comparative Examples 2 and 3, the polymer gelled and a benzene-soluble polymer was not obtained.

Further, in Comparative Examples 4 and 5, no improvement in the heat resistance of the polymer was observed.

Example 11 Cuprous bromide 0.299 and N, N, N',
The same procedure as in Examples 1 to 5 was carried out, except that 0.15 × 9 of N'-tetramethyl-13-butanediamine was used, and 2,6-dimethylphenol alone dissolved in benzene was used as the raw material solution. Additive-free poly(2,6-dimethylparaphenylene ether) was obtained, and 1 wt% of 2,6-diphenylphenol was added to 26-dimethylphenol without removing the catalyst, and the mixture was further heated for 2 hours.
The reaction was carried out while introducing 1 oxygen.

At that time, the temperature at which weight loss started was 427°C. Example 12 Additive-free poly(2,6-dimethylparaphenylene ether) was prepared in the same manner as in Examples 1 to 5 above, except that only 2,6-dimethylphenol dissolved in benzene was used as the raw material solution. ) 209, and once the catalyst was removed, this polymer was mixed with 0.299% of cuprous bromide and 3.0% of pyridine.
29 and 0.29 of 2,6-diphenylphenol were added, and the reaction was carried out for 2 hours while introducing oxygen.

Claims (1)

[Claims] 1 When 2,6-dimethylphenol is polymerized using an oxygen-containing gas in the presence of a copper-amine catalyst, 2,6
- Adding 0.05 to 10 wt% of 2,6-diphenylphenol to dimethylphenol to give 20 to 50%
Heat-resistant poly(2,6-
Production method of dimethyl paraphenylene ether).